What to make of chat show presenter Paul O’Grady spending £8,000 worth of veterinary fees on his cairn terrier, Olga? It’s utterly insane! It’s bonkers! It’s sentimental anthropomorphism of the slushiest sort!

Moreover, even though the 58-year-old television star can well afford to take the hit, and it’s a fraction of the cost of a new kitchen, isn’t lavishly bankrolling cancer treatment for a dog morally dubious?

Of course it is. Until your dog – your beloved family member – becomes poorly, when suddenly it all makes perfect sense.

I should know. I have on my desk a stack of vet’s bills in excess of £3,600 for blood profiles and diagnostic ultrascans and a kidney biopsy that had to be sent to a biological research facility in Texas for analysis.

Hand on heart, I never thought I would be the sort of person to pay for my dog to have anything more invasive than a microchip and the odd jab. But when Daisy, our six-year-old Manchester terrier, was diagnosed with a kidney impairment at the end of last year, having lost her relentless joie de vivre and developed painful swellings on her body, all my principles went out the window.

It helped that we have pet insurance, but it rapidly became clear that its upper limit of £3,000, which we had thought generous, wasn’t going to be enough to cover the initial costs, never mind any ongoing drug treatments she might need.

Daisy was treated at the Royal Veterinary College Hospital, near Potters Bar, north of London, a place of such tranquillity and professionalism, I’d be happy to place my own health in their hands.

It’s not cheap, but the length of the consultations, the listening ear – and the fact the staff telephone you twice a day updating you on your animal’s condition (something NHS users can only dream of) do help you feel you’re getting your money’s worth.

At our first appointment, the vet explained the initially-quite-conservative tests they were going to run for a mere £1,200. When I gave an audible intake of breath, she replied: “I could spend £15,000 easily on Daisy in 15 minutes.”

“Doing what? I spluttered. “Online gambling?”

But the thing is, caring for an ailing pet isn’t about the cash. At least not at first. It’s about repaying loyalty and unconditional love.

O’Grady’s previous rescue dog, Buster, a shih tzu-bichon frisé cross, also had cancer and was put down, aged 14, in 2009. So when Olga was diagnosed with cancer of the kidney and given 18 months to live, he didn’t hesitate to pay for surgery, and then chemotherapy, and said he would sell his house to pay for treatment.

It would be cheaper to invest in top-notch pet insurance. Some £1.6 million is spent on cover every year by half of Britain’s 14 million pet owners. Vet fees have doubled in a decade, and are rising at an annual rate of 12 per cent. Moreover, with the average bill now £300, it makes sense to pay a monthly premium.

However, premiums themselves are rising at 15 times the rate of inflation, which the industry claims is due to expensive technological developments in care.

Not all insurance policies provide cover for the same conditions, and it is also notoriously tricky to make claims on pet insurance, something that has come to the attention of the Financial Ombudsman Service, which is finding in favour of pet owners in two thirds of cases.

Stories are legion of people who aren’t able to recoup the cost of procedures excluded in the small print. Last year, 33-year-old office worker Vicky Hughes from Staffordshire paid £4,000 for emergency surgery on her Dogue de Bordeaux, which had collapsed with a slipped disc. When her pet insurer rejected her claim, she resorted to selling her kitchen appliances and clothes on eBay to fund treatment.

Debbie and Vince Weston, who had no insurance, were forced to remortgage their home to pay for the £15,000 emergency surgery their Hungarian vizsla cross, Blue, needed after running in front of a train.

That’s a lot of debt, but in life-or-death situations split-second decisions have to be made. And once you start the treatment process it’s hard to draw a financial line over which you will not step.

Daisy has perked up considerably thanks to a special diet and three different medications a day. But, much as I – we all – adore her, we have drawn that line. I won’t be ferrying her in and out of vet hospital for regular tests. She’s finds it horribly stressful, as do I.

We were told by the vet she might have days to live, but weeks have extended into months and her good days still outnumber the bad.

So we are going to enjoy her as much as we can, in whatever time we have left. At the point when there are no more good days, we will make the heart-rending decision to have her put down. Call me a sentimental old anthropomorphist, but sometimes being a dog’s best friend means letting them go.